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(1/141) Pharmacokinetics of prilocaine after intravenous administration in volunteers: enantioselectivity.

BACKGROUND: Prilocaine exists in two stereoisomeric configurations, the enantiomers S(+)- and R(-)-prilocaine. The drug is clinically used as the racemate. This study examined the pharmacokinetics of the enantiomers after intravenous administration of the racemate. METHODS: Ten healthy male volunteers received 200 mg racemic prilocaine as a 10-min intravenous infusion. Blood samples were collected for 8 h after the start of the infusion. Plasma concentrations were measured by stereoselective high-performance liquid chromatography (HPLC). Unbound fractions of the enantiomers in blank blood samples, spiked with racemic prilocaine, were determined using equilibrium dialysis. RESULTS: The unbound fraction of R(-)-prilocaine (mean +/- SD, 70%+/-8%) was smaller (P < 0.05) than that of S(+)-prilocaine (73%+/-5%). The total plasma clearance of R(-)-prilocaine (2.57+/-0.46 l/min) was larger (P < 0.0001) than that of S(+)-prilocaine (1.91+/-0.30 l/min). The steady-state volume of distribution of R(-)-prilocaine (279+/-94 l) did not differ from that of S(+)-prilocaine (291+/-93 l). The terminal half-life of R(-)-prilocaine (87+/-27 min) was shorter (P < 0.05) than that of S(+)-prilocaine (124+/-64 min), as was the mean residence time of R(-)-prilocaine (108+/-30 min) compared with S(+)-prilocaine (155+/-59 min; P < 0.005). CONCLUSIONS: The pharmacokinetics of prilocaine are enantioselective. The difference in clearance is most likely a result of a difference in intrinsic metabolic clearance. The difference in the pharmacokinetics of the enantiomers of prilocaine does not seem to be clinically relevant.  (+info)

(2/141) Topical anaesthesia of intact skin: liposome-encapsulated tetracaine vs EMLA.

In this randomized, double-blind study, we have compared the ability of 5% liposome-encapsulated tetracaine (amethocaine) (LET) vs 5% eutectic mixture of local anaesthetics (EMLA) to produce local anaesthesia of intact skin in 40 healthy volunteers. Volunteers had both preparations applied to their forearms under an occlusive dressing for 1 h. Superficial anaesthesia was measured by a total of nine 1-mm pinpricks on each arm. Deeper anaesthesia was assessed by single insertion of a sterile 22-gauge needle to a depth of 3 mm and pain was reported on a visual analogue scale (VAS). If the volunteer perceived greater than four of the 1-mm pinpricks, the 3-mm insertion was not performed. Results showed that the number of pinpricks perceived was significantly less (P < 0.01) for LET (median 1.0; range 0-9) vs EMLA (1.5; 0-9). In volunteers who had deeper anaesthesia assessed, there was no significant difference (P = 0.065) in VAS scores for LET (mean 1.5 (SD 1.4); n = 34) vs EMLA (2.4 (2.1); n = 28). Overall anaesthetic effect, as ranked by all of the subjects, was significantly better for LET compared with EMLA (P = 0.024). We have demonstrated that when applied in equal volumes, 5% LET produced better superficial local anaesthesia than EMLA.  (+info)

(3/141) Bone marrow harvesting using EMLA (eutectic mixture of local anaesthetics) cream, local anaesthesia and patient-controlled analgesia with alfentanil.

Bone marrow harvesting (BMH) was performed on 40 consecutive allogeneic or autologous donors using EMLA (eutectic mixture of local anaesthetics), local anaesthesia (LA) and patient-controlled analgesia with alfentanil (PCA-A). The effect of alkalinizing the LA solution on reducing pain during LA infiltration in the presence of EMLA was also investigated. EMLA 10 g with occlusive dressing was applied to the harvest sites at least 60 min before BMH. The PCA device was programmed to deliver an intravenous loading dose of 15 microg/kg alfentanil, followed by a background alfentanil infusion of 0.05 microg/kg/min. Demand dose was 4 microg/kg and lockout time was 3 min. Donors were randomized to receive either alkalinized (n = 19) or non-alkalinized (n=21) LA solution (lignocaine 1% with 1:100000 adrenaline). While post-operative nausea and vomiting were the only side-effects, all donors in both groups reported satisfactory pain scores during LA infiltration and satisfactory overall intra-operative comfort scores. They completed BMH using either regimen successfully, found this technique acceptable and would recommend this form of anaesthesia to others. Alkalinizing the LA solution did not significantly improve the pain scores during LA infiltration in the presence of EMLA. In conclusion, BMH can be performed safely using EMLA, LA and PCA-A without major complications.  (+info)

(4/141) Tetracaine gel vs EMLA cream for percutaneous anaesthesia in children.

We have evaluated the anaesthetic effect of tetracaine gel 1 g, applied for 45 min, compared with EMLA cream 2 g, applied for 60 min, in a randomized, double-blind study in 60 children aged 3-15 yr. Venous cannulation was performed 15 min after removal of the EMLA cream (n = 20) and tetracaine gel (n = 20). Cannulation was performed up to 215 min after removal of the tetracaine gel in another 20 patients. Significantly lower pain scores were recorded by the children treated with tetracaine gel compared with EMLA cream (P < 0.02). Forty to 45% of children in the tetracaine groups reported no pain compared with only 10% in the EMLA group. Only minor adverse effects were observed. We conclude that tetracaine gel provided effective, rapid, long-lasting and safe local anaesthesia, and was significantly better than EMLA cream in reducing pain during venous cannulation in children using the recommended application periods for both formulations.  (+info)

(5/141) A comparison of local anaesthetics for venepuncture.

AIM: To compare the effectiveness of EMLA cream and Ametop gel in providing analgesia for venous cannulation. METHODS: Single blind study in 120 children. RESULTS: Both anaesthetic agents produced adequate analgesia. However, Ametop gel was more effective, with a statistically significant difference in the pain scores of the two groups (p < 0.05).  (+info)

(6/141) Both EMLA and placebo cream reduced pain during extracorporeal piezoelectric shock wave lithotripsy with the Piezolith 2300.

BACKGROUND: The objectives were to determine whether a eutectic mixture of local anesthetic (EMLA) or placebo cream reduces pain during extracorporeal piezoelectric shock wave lithotripsy (EPSWL), and to determine which of the components of the application (i.e., the occlusive dressing, the cream, or the local anesthetic) contributes to analgesia. METHODS: A randomized, double blind, crossover study (part 1) was performed in 12 patients who were scheduled for EPSWL procedures on an ambulatory basis who received the first treatment without any intervention and who had verbal pain scores of 70 or more (on a 0-to- 100 scale). For the next two treatments at 2-week intervals, patients were randomly assigned to receive either 10 g EMLA or 10 g placebo cream and then crossed over to receive the other. The cream and occlusive dressing were left in place and immersed in water throughout the procedure. Verbal numeric pain score was assessed at 5 min after receiving the maximal tolerable intensity of shock wave and at the end of the procedure. The study continued (part 2) in 202 ambulatory patients; 125 men and 77 women, American Society of Anesthesiologists physical status I and II, subjected to EPSWL were randomly allocated into five groups who received (1) nothing on the skin (control), (2) plastic occlusive dressing, (3) placebo cream and plastic occlusive dressing, (4) EMLA cream and plastic occlusive dressing, (5) EMLA cream and plastic occlusive dressing for 60 min to achieve cutaneous anesthesia, which was removed before EPSWL. Pain score was evaluated 10 min into the procedure and at the end of the procedure. RESULT: Both parts of the study showed that patients who received either EMLA or placebo cream with dressing throughout the procedure experienced less pain and tolerated higher energy levels compared with the control. Patients who received only pre-EPSWL cutaneous anesthesia of EMLA and who received only the occlusive dressing did not have a reduction in pain score. CONCLUSIONS: EMLA and placebo creams under occlusive dressing reduced pain during EPSWL. The presence of the cream itself as a coupling medium contributed to analgesia. This may be a useful, simple, safe, and economical adjuvant technique to reduce pain during immersion EPSWL.  (+info)

(7/141) Evaluation of prilocaine for the reduction of pain associated with transmucosal anesthetic administration.

This investigation evaluated the use and efficacy of prilocaine HCl (4% plain Citanest) for minimizing pain associated with the intraoral administration of local anesthesia. Clinical anecdotes support the hypothesis that prilocaine without a vasoconstrictor reduces pain during injection. To determine relative injection discomfort, use of 4% plain prilocaine was compared with use of 2% lidocaine with 1:100,000 epinephrine and 2% mepivacaine with 1:20,000 levonordefrin. Prior to routine endodontic procedures, 150 adult patients received 0.3 to 1.8 mL of local anesthetic via the same gauge needle without the use of a topical local anesthetic. Injection methods included buccal infiltration, labial infiltration, palatal infiltration, and inferior alveolar nerve block. Following each injection, patients were asked to describe the level of discomfort by scoring on a visual analog scale of 1 to 10, where 1 = painless and 10 = severe pain. Analyses via 2-way analysis of variance revealed no interaction between anesthetic and site of injection. However, there were statistically significant differences among the injection sites. Post hoc analysis revealed that prilocaine was associated with significantly less pain perception when compared to mepivacaine and lidocaine. These results suggest that differences in initial pain perception during transmucosal injection may be a function of the local anesthetic use, and prilocaine can produce less discomfort than the others tested.  (+info)

(8/141) A randomised, double-blind, placebo-controlled, comparative study of topical skin analgesics and the anxiety and discomfort associated with venous cannulation.

OBJECTIVES: To compare the effect of topical skin anaesthetic agents on the discomfort and anxiety associated with venous cannulation. DESIGN: Randomised, double-blind, placebo-controlled, within subject, volunteer trial. METHODS: 20 healthy volunteers underwent venous cannulation on three separate occasions having received topical skin application of either 4% amethocaine gel (Ametop), 5% eutectic mixture of lidocaine and prilocaine (EMLA) or E45 cream (placebo). Visual analogue and verbal rating scales were used to assess pain and anxiety associated with the venous cannulation, and anticipated anxiety for future cannulation, under each drug condition. RESULTS: Subjects were aged 22-53 years (mean 32.8 years). The mean visual analogue scores (VAS) for discomfort were found to be significantly lower (p< 0.001) with Ametop (VAS = 18mm) and EMLA (VAS = 29mm) compared with the control (VAS = 38mm). There was a positive correlation (R2 = 72%, p<0.001) between discomfort and the predicted anxiety if cannulation was to be repeated with the same cream. With the placebo a positive correlation (R2 = 19.8%, p = 0.05) was found between the level of anxiety before cannulation and the level of discomfort recorded. CONCLUSIONS: Ametop and EMLA topical anaesthetic agents produce effective skin analgesia for venous cannulation. The use of topical analgesia can reduce perceived anxiety about future cannulation procedures. This has application in the management of anxious patients undergoing intravenous sedation, suggesting that topical analgesia prior to venous cannulation may significantly aid anxiolysis.  (+info)